Crowns are fixed restorations, and there are many forms of fixed restorations, such as veneers, inlays and full crowns. A veneer is a layer that is placed on the surface of the tooth, which requires grinding off a very thin layer of tooth tissue and gluing it on the surface, called a veneer; there is also a restoration called an inlay, which is a restoration of a partial tooth defect with very little tooth grinding. It has the advantage of being more precise than traditional fillings, and without the polymerization and shrinkage of resin, it has a better long-term effect. There is another type of restoration that is known as full crowns, or what is commonly referred to as braces. In the case of full crowns, the amount of preparation is larger, and more tissue needs to be removed, and the whole tooth is placed inside the crown, so the people call it braces. There are many different materials for braces, including metal, porcelain, all-porcelain, all-porcelain is divided into cast porcelain, zirconia porcelain. There are many different types, and the doctor will decide which restoration to choose based on the patient’s specific situation.